Temperature ratings of fire sprinkler

What are Temperature Ratings of Fire Sprinkler and their Color Codes?

Such as on glass bulb or fusible link area. If you observe closely then you can find some codes related to temperature ratings of fire sprinkler. Yes, you can find markings on transparent part of glass bulb and also you will observe markings on frame of fire sprinkler using fusible link.

Not only temperature ratings you will also see the glass bulb having glycerin based liquid with different colors.

Next you will have a question in your mind that, what are temperature ratings of fire sprinkler and colors of sprinklers and what the use of this ratings and colors is.

Now let I explain you the concept in a very simple way step by step.

What are this markings on sprinkler?

temperature ratings

Every fire sprinkler with glass bulb or with fusible metal link, they are all engraved with codes related to temperature ratings and with different colors. You can see this ratings on frame or deflector in beside image. The markings on sprinkler will have following details

  • Sprinkler Type(Pendent/Upright/Quick response, etc.,)
  • Temperature Rating
  • Year of Manufacture
  • Model number
NOTE: Read the article to know about “Types of Fire Sprinkler Heads

Why fire sprinklers are with temperature ratings?

When we are going to design a sprinkler system for any type of building, first of all we want to know which type of sprinkler system, which type of piping and which type of sprinklers are to be used for that building.

If we want to select the type of sprinkler, then its characteristics help us to identify the appropriate sprinkler to be used. The sprinkler characteristics such as thermal sensitivity, temperature ratings, k-factor and other special ones will give information.

All Fire sprinklers are designed at different temperature ratings. The liquid in the glass bulb expands when the surrounding temperature reaches a certain level. And then it breaks the bulb and allow water to pass through the pipes toward deflector.

Buildings like residential, commercial, and industrial ware houses all have different temperatures. So the sprinklers used at different sectors need to be operate at different temperatures. They have to withstand the high temperatures as well as moderate temperatures.

This is the reason why these sprinklers are designed to withstand at different temperatures. Now let us have a look on Thermal sensitivity and Temperature ratings and their color codes.

Thermal Sensitivity

The Thermal Sensitivity of the sprinkler indicates that the responding nature of sprinkler i.e., quickly or normally. Based on Thermal sensitivity the sprinklers are categorized into following

  • Standard Response
  • Fast Response

Standard Response

This type of sprinklers will have the glass bulb of thickness 5mm. These are the most common type of sprinklers used generally.

Fast Response

This category type of sprinklers respond soon than the other standard type of sprinklers. These sprinklers will have the glass bulb thickness about 3mm. Quick response sprinklers are one of the examples of fast response sprinklers.

Temperature Ratings

As we discussed above at starting, if we observe sprinklers closely the glass bulbs will have different colors in different sprinklers.

These all colors will represent the temperature ratings of fire sprinklers. Different colors for different temperatures.

As per NFPA 13 standards for fire sprinklers we can have various characteristics of fire sprinklers need to be.

The following table provide details of temperature ratings of the fire sprinklers with different colors as per NFPA 13 standards for fire sprinklers.


Now finally, after reading the above content you can have a basic knowledge regarding thermal sensitivity, temperature ratings of fire sprinklers and color codes of sprinklers.

So we have to take this characteristics into consideration while we designing the sprinkler system of a building. It is also important to take care that the sprinklers in a same area or room or compartment are not to be with different temperature ratings.

Because when fire accident happens, the all sprinklers will not operate at same time. There is chance of skipping of operation of sprinklers.

So if you have any comments and suggestions regarding this article please comment below. And also please share the article if it helps you to understanding the concept of temperature ratings of fire sprinklers and their color codes.

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By Naseer Shaik

Hi, I am Naseer Shaik, Mechanical Engineer. Present working as Plumbing and Firefighting Engineer in Kuwait. And also I am a Blogger, YouTuber.

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